This was Mayor Rahm Emanuel being Mr Tough Guy to show the world that they can come for G8 and Nato. It's as simple as that. There was no need to make mass arrests on this night. There was no need to show Mr Tough Guy. It was a show of force. It was stupid."

The evidence is starting to point that way. Shortly before 11pm, on Saturday 15 October, a police supervisor with rank told the Occupy protesters that they were going to be allowed to stay in Grant Park and protest, so long as they kept the volume down. It was actually an ironic moment when the "human microphone" started urging protesters, in its uniquely reiterative way, to be quiet so that guests in the neighboring hotels could sleep. It had a surreal element to it – but that fit nicely with the performative aspects of the Occupy movement.

It also matched the circumstances of the protest. The assembled group of about 700 protesters (down from 2,000 to 3,000 because of the looming fear of arrest) was entirely peaceful, well-dressed, and respectful. To any reasonable police professional, this did not call for mass arrests.

Protesters were surprised when, later, the Chicago Police Department announced that anyone who did not vacate Grant Park and walk across the street on Michigan Avenue (where the police appropriately exercised its discretion and allowed continued protest) would be arrested – which they were. They were then cuffed, booked, fingerprinted, detained in jail some for up to 17 hours, placed on bond with travel restrictions, and prosecuted in criminal court.

For a long time, it has been a mystery as to why the police turned around. But the mystery may now be solved. Here's verbatim from the affidavit that the presiding judge, Judge Thomas More Donnelly, reviewed yesterday:

At approximately 10.15pm, a leading organizer with Occupy Chicago, flanked by Chicago police officers, made an announcement over our PA system that one of the officers in charge had told us that while we would be violating the park curfew, we would be allowed to remain in the park as long as we kept the noise down so as to not disturb guests in hotels across the street. The police officers flanking the organizer, who did not raise any protest but rather remained silent, gave to this announcement the air of officialdom. Several officers nearby me seemed to further validate the official character and finality of this statement by expressing their excitement that they would soon be able to leave Grant Park. The police did not disperse, however, and approximately 20 minutes later, a police officer who appeared to be in charge reiterated that we would have to leave the park by 11.00pm. This resulted in considerable confusion and uncertainty for all present. After this second announcement, I heard many individual officers comment that it was Mayor Rahm Emanuel who had intervened and insisted that we be asked to leave the park … We continued to interact peacefully with the police. The police officers whom I spoke with after 11 gave me the impression that they were waiting for a political decision to be made regarding our situation."

Durkin may well be right that the arrests were "a 'dry run' by the Emanuel administration for handling protests during the G8 and Nato summits in May."

Another interesting tidbit from the hearings: Joey Mogul, an attorney at the People's Law Office and one of the lead attorneys on the recent $6.2m Chicago Police Department settlement for improper arrests at the 2003 anti-war rallies – does anyone see a pattern? – leaned over to me with a fascinating question: if the City is arguing that the parks need to be closed at night from 11pm to 6am, then how come they remain open for corporate speech 24/7? Aren't the McDonald's, Chase, Exelon, Boeing, etc, signs, advertisements, images, also speech? How come they get to be there 24 hours a day?

A quick look at Chicago's Millenium Park gives you a vague idea of how much corporate speech litters the park. This is from Wiki, but check out their own map here.

The mass court hearings resume Thursday at 1.30pm at the Daley Center. The presiding judge was shocked to hear, yesterday, that the 300 arrestees has been placed under bond with travel restrictions and been told that they could not travel over the winter holidays because of their court cases. The judge was palpably astonished. It's completely outrageous given how peaceful and articulate the Occupy protesters are in Chicago.